Confession is something you might do when you feel bad about something wrong you have done or said. It's like when you accidentally knock over a vase and then feel really bad about it. Confession is when you say sorry for your mistake to a religious leader or a priest who listens to your confession.
In some religions, like the Catholic Church, confession is seen as a way to seek forgiveness from God. You go into a private room, called the confessional or reconciliation room, to tell the priest what you did wrong. The priest listens to you without judging you and then gives you a penance. A penance is like a punishment or something good that you can do to show that you are sorry and want to make things right.
Once you have done your penance, the priest forgives you on behalf of God. This is called absolution. It means that God has forgiven you and you can feel better knowing that you are back in a good relationship with God.
Confession is a way to make things right with God and to feel good about yourself again. It's a way to show that you are sorry and that you want to be a better person.